The present invention relates to an air-intake device for drawing air into a liquid dispenser.
A liquid dispenser is generally equipped with a rigid reservoir and with an atmospheric pump provided, in particular, with a cylindrical and conical body and with a support flange co-operating, as applicable, with an assembly ring or with an assembly cap crimped to the neck of the reservoir.
A metered quantity or xe2x80x9cdosexe2x80x9d of liquid being dispensed generates suction in the fixed-capacity reservoir, and it is necessary to compensate for said suction by drawing in a corresponding volume of air. To this end, the pump body is provided with vent orifices suitable for putting the internal volume of the reservoir into communication with the outside during the final stage of dispensing.
Another technique for re-establishing the pressure balance necessary for the dispenser to operate properly consists in providing clearance between the fixing flange and/or the pump body and the neck of the reservoir and/or the assembly cap so as to enable air to be sucked in.
However, in all known techniques, the vent-forming means also enable liquid to leak out, especially when the level of liquid is above the vent, either by construction or by the dispenser being used specifically in the upside down position.
An object of the present invention is to solve those technical problems satisfactorily without modifying the conventional structure of dispensers.
The invention achieves this object by means of an air-intake device characterized in that it comprises a sleeve designed to be fitted around said body of the pump, under said flange, and having its bottom portion provided with a vent-forming collar whose inside wall which serves to come into radial clamping engagement against said body has a surface state such that said collar is both impermeable to the liquid and also permeable to air.
In a specific embodiment, the surface of the inside wall of said collar has grains resulting from electrical discharge machining.
According to an advantageous characteristic, above said collar, said sleeve co-operates with the wall of said body to define an empty space suitable for communicating with the outside by forming at least one suction duct for drawing air in.
In a variant, said empty space is defined by at least one groove extending over the outside side wall of the body of the pump. This variant applies more particularly to pumps equipped with a vent orifice by construction.
Preferably, in the free state, the inside diameter of said sleeve is less than or equal to the outside diameter of the body in the vent zone. In addition, the top edge of said sleeve then comes into abutment against said flange.
In another variant, said empty space is formed by the gap situated between the inside wall of the sleeve and the outside side wall of the body of the pump, above the collar. This variant applies particularly to pumps not provided with a vent orifice.
Preferably, the top portion of said sleeve is then provided with crenellations making it possible for air to be drawn in laterally.
Advantageously, the collar is frustoconical in profile, while the sleeve is cylindrical and has a top edge that is beveled. The device of the invention makes it possible to draw in sufficient air while also guaranteeing that the dispenser is airtight.
The static liquid-tightness of the collar may be adjusted as a function of the viscosity of the liquid to be packaged. The sleeve of the invention may be put in place after the pump has been manufactured without it being necessary to modify said pump.
In addition, the sleeve is applicable to precompression pumps with or without vent orifices.